Denitrogenation of petroleum



Jan. 9, 1962 A. A. OSWALD ET AL 3,015,349

DENITROGENATION OF PETROLEUM Filed Aug. 10, 1959 DISTILLATION TOWERL PREHEQTER DEPYRROLIZED 6 m M PagoucT L J MYA WW 4 7 4 ll SETTLER CRUDE OR DISTILLATE NITROGEN RICH BOTTOMS Jr DEPYRROLIZER PEROXIDE lexis 7 ernun 06 Ch l Ru or INVENTORS Stephan llnyc yj W Q PATENT ATTORNEY United States Patent 'DENITROGENATION OF PETROLEUM Alexis A. Oswald, Charles B. Rupar, Stephan Ilnyckyj,

and Fernand Noel, all of Sarnia, Ontario, Canada, assignors to 'Esso Research .and Engineering Company,

a corporation of Delaware Filed Aug. 10, 1959 Sen-No. 832,734 8 Claims. ((31.208-254) fractions when they are employed, for example, as middle distillate fuels. Filters and fine orifices, such as burner nozzles and fuel injectors, become plugged rapidly.

In recent years the problem has become more acute. Because of the increasing demand for middle distillate fuels,- petroleum refiners have been forced to include higher boiling fractions and catalytically cracked gas oil in heating oils. The addition of these components aggravates the sediment'formation.

A "further problem of stability has been encountered with jet fuels needed for high performance military aircraft. Jet fuels are often used as a heat exchange medium for cooling the engine lubricating oil. This requires the exposure of the fuel to temperatures in the order of 500 F. for short periods of time. Sediment formation is accelerated .at these high temperatures, filters are rapidly plugged, and frequent and costly maintenance of the fuel :system is required.

'It is well known that alkylated pyrroles and indoles, mainly of the dialkylated type are constituents of petroleum fractions. "See Sauer et al., Industrial and Engineering Chemistry, Vol. 44, p. 2606 (1952). his also well known that these constituents are the main color and sludge formers in many fuels. -See Dinneen et al., Industrial and Engineering Chemistry, Vol. 43, p. 1604 (1951'); Chenice'k et al., Industrial and Engineering Chemistry, Vol. 43 p. 935' (1951). In addition pyrrolic nitrogen compounds actas catalyst poisons during further processing.

In the past, treating methods :such as sodafining, acid treating and hydrofining and the incorporation of a variety of additives have been :used to control sediment formation. Though these approaches have met with some success they are often unsatisfactory and erratic.

In accordance with this invention, it has been found that the addition of organic peroxides at temperatures between 50 to 250 F. and the addition of organic sulfides and sulfoxides at temperatures between 60 to 350 F. to petroleum products results in the conversion of nitrogen compounds of the pyrrole type to higher boiling compounds. On subsequent distillation the major proportion of these contaminants remains in the bottoms and a stabilized overhead product is obtained.

To further illustrate the invention, reference is made to the accompanying FIGURE, which shows a preferred process for the removal of pyrrole type compounds from a petroleum crude or distillate. A petroleum crude or distillate is fed to a depyrrolizer 1 through lines 2 and '3.

The distillate may be a narrow cut or may include the whole crude boiling range. Where the feed is crude, water, sediment and salt are usually removed before the Patented Jan. 9, 1962 are removed from the bottom of settler 6 through line 9.

The sediment-free overflow then passes from the preheater 8 to distillation tower 10 through line 11. Erom this tower either a depyrroliZ-ed distillate of wide boiling range or depyrrolized distillate fractions are obtained ready for use or further process. "If the peroxide added to the feed is not wholly consumed in the depyrrolizer,

the product from the settler 6 can be washed with aque-- ous causticbefore going to the preheater 8.

.A wide variety of organic peroxides may be used to denitrogenate petroleum hydrocarbons in accordance with the invention. Acyl peroxides, peracids, alkyl and aralkyl hydroperoxides, dialkyl peroxides are examples of the materials that may be utilized. By way of illustration, specific compounds include benzoyl peroxide, -4-chlorobenzoyl peroxide, 2,4-dichlorobenzoy1 peroxide, peracetic acid, t-butyl hydroperoxide, cumene hydroperoxide and bis-t-butyl peroxide.

The preferred ranges on the amount of peroxide added are dependent on the concentration of the pyrro'lic =n'itrogen compounds in the oil to be 'depyrrolized. About 0.1-5 moles of peroxide per mole pyrrole in the oil can be used but it is preferred to use peroxide tquantities between 0.5 and 3 moles of peroxide per mole'pyrrole. The use of greater than molar quantity of peroxide is some times necessary because of side reactions with other "fuel Precipitation of pyrrole nitrogen from benzene components.

Though the above illustration shows the removal of the concentrated nitrogen phase (sediment) from the stabilized petroleum product by distillation, other meth-' ods of separation may be employed. For example, the hydrocarbon insoluble, solid products of peroxide-pyrrole reactions can be removed by filtration from the treated petroleum fraction. Any excess of hydroperoxide reagent can be converted to sodium salt by aqueous caustic and extracted as water phase subsequent to filtration. Filtration can be-also followed by extraction with. a highly polar solvent such as ethylene glycol or phenol.

To further illustrate the advantages of "the instant invention the following examples are given. In the .first several examples controlled .amounts of pyrrole were added to liquid hydrocarbons .to simulate the composi tions of petroleum fractions.

EXAMPLE 1 solution with benzoyl peroxide I To a benzene solution (50 ml.) containing 3.35 grams (0.05 mole) of pyrrole, 12.1 grams (0.05 mole) of benzoyl peroxide were added. The mixture was stirred for half an hour with a magnetic stirrer, and "left standing for 3 days at room temperature. A subsequent filtation recovered a heavy black sediment. This sediment was washed with benzene .and naphtha (50 ml. each) and then extracted twice with 500 ml. boiling water for 20 minutes. The remaining insoluble residue weighed 1.5 grams after drying.

An elemental analysis of this residue revealed the fol- Such a composition of matter may have the structure of a pyrrole black for which the following formula is proposed:

ULC/U or For the proposed composition, (C19H1304N3)fl, the calculated values are:

Found Carbon 65.54 Hydrogen 4.01 Nitrogen 12.01

Thev action of other acyl peroxides (4-chlorobenzoyl peroxide, 2,4-dichlorobenzoyl peroxide) on benzene solutions containing pyrrole was similar to that of benzoyl peroxide.

EXAMPLE 2 Precipitation of pyrrole nitrogen with benzoyl peroxide in the presence of t-dodecyl mercaptan A solution of 12.1 grams (0.05 mole) of benzoyl peroxide in 50 ml. benzene was added to a mixture of 3.35 grams (0.05 mole) of pyrrole and 3.7 grams (0.017 mole) of t-dodecyl mercaptan. The mixture which became immediately black was treated in the manner described in Example 1. About 2.3 grams of a black powder was obtained, which contained 13.4% nitrogen and 0.28% sulfur.

EXAMPLE 3 Formation of a residue of a high nitrogen content by a reaction between cumene hydroperoxide and pyrrole in benzene solution To 25 ml. benzene solution of 13.4 grams (0.2 mole) of pyrrole, 30.6 grams (0.2 mole) of cumene hydroperoxide was added and the resulting mixture was refluxed for 2% hours. Benzene was removed from the resulting orange solution by distillation at mm. pressure. On distilling the residue 8 grams of a yellow liquid containing 3.8% N were obtained between 84 to 86 C. at 2 mm. The residue was a purple solid weighing 4 grams. An analysis revealed that this residue contained 13.8% N.

EXAMPLE 4 The precipitation of pyrrole nitrogen from benzene solution by cumene hydroperoxide A'benzene solution (333 ml.) containing 2.2 grams (0.33 mole) of pyrrole and 15.2 grams (0.1 mole) of butyl hydroperoxide was kept in an open 500 ml. Erlenmeyer flask for 2 weeks at 110 F. At the end of this period, the reaction mixture was filtered and the precipi- 4 sediment was determined. The results are shown in the following:

EXAMPLE 6 Removal of nitrogen by peroxide treatment from cata- 666 F. final boiling point.

lytically cracked untreated gas oil (a) Control.-One liter of an untreated catalytically cracked gas oil was heatedup at a rate of 40 C. per hour to 90 C. in an open 2 liter round bottom flask on a steam bath. Then the oil was kept at the same temperature for 6 hours. After this time, the oil was distilled and nitrogen and sulfur concentrations were determined in the 20 to 90% overhead distillate and in the 10% residue.

(b) t-Butyl hydroperoxide treatment.--To one liter of the oil used above 13.5 grams (0.15 mole) of butyl hydroperoxide were added. Then the oil underwent the same treatment as the control. The treated oil was washed free of butyl hydroperoxide by 0.1 N aqueous NaHSO and distilled in the same manner as the control.

(c) Diacetyl peroxide treatment.To one liter of the above oil 17.7 grams (0.15 mole) of diacetyl peroxide were added. Then the oil was heated up at a rate of 40 C. per hour to 90 C. and kept there for 2 hours. After that period, it was worked up as under (b).

The results of these experiments are shown in the fol- 0.5 wt. percent of 2,4-dichlorobenzoyl peroxide was added to catalytically cracked gas oil and the solution kept at 200 F. for two hours. Product was distilled to 95.3% yield of the product was realized.- 50% of nitrogen was left in distillation bottoms. The results are shown below: tate formed 1s shown as m1llxgrams/100 ml. in the fol- TABLE II lowing. table compared with data for the blanks with only one of the reagents. Nitrogen Wt Per eixt e0 Added Compound fied lgelp t Npercent N P Kid 0 em 9 g Peroxide Treat Treat gymh H d dd 0333512205 63053;. n y'aras'staasj: 400 "it-t caewaany 00001000 G05 011 0.000

Distillation Overhead, 666 F.,-FBP 0.028 0.015

re nants: as.

"' ie 0 e St a ea 96.8 95.3 EXAMPLE '5 The precipitation of 2,5 -dimethylpyrrole by hydroper- EXAMPLE8 oxides To 100 ml. cetane solution containing 2.8 grams (0.03 mole) of 2,5-dimethylpyrrole, equimolar (0.03 mole) quantity of hydroperoxide was added. The mixture was stored in an open 250 ml. Erlenmeyer flask at 110 F. for 24 hours. At the end of this period the insoluble Two grams (0.03 mole) of pyrrole were dissolved in ml. of benzene. To the solution 9.3 grams (0.03 mole) of (2-hydroperoxy-2-phenyl)-propyl Z-naphthyl sulfide, the hydroperoxide prepared in Example 2 of copending application U.S. Serial No. 777,617, was added and the solution was placed into an oven at F.

Qbservations After 16 hours at 110 F.

Components in Benzene Solution (each in 0.3 m/lcc.)

Sediment mg. 100 ml.)

Color (Tag- Robinson) Y 582 Nil Nil 'Hydreperoxide Pyrrole Hydroperoxide Pyrrole The sediment was produced by the reaction of the hydroperoxide with the pyrrole. This is shown by the results of an analysis made of the sediment which revealed it to contain 7.4% nitrogen and 7.5% sulfur. The solution containing the hydroperoxide alone did not contain any sediment but on further standing precipitated colorless crystals which upon analysis showed them to be without any peroxide character. The solution containing pyrrole alone gave no evidence of precipitation after several hours of standing.

An alternative method for removing nitrogen compounds is by the forming of the peroxide in situ from added reactive hydrocarbons. This can be done by oxidizing suitable added hydrocarbons in the petroleum fraction containing the nitrogen compounds. The addition of aliphatic hydrocarbons containing activating groups is preferable because they are easier to peroxidize. Such activated hydrocarbons are, for example, cumene, styrene, indene and octadecene. Oxidation can be accomplished by using molecular oxygen (air) or active peroxides. Ultraviolet light, peroxides, etc., may be employed as oxidation catalysts. 7

The following example is illustrative of this modification of the invention.

EXAMPLE 9 Formation of a residue of high nitrogen by reacting i dene peroxide formed in situ with pyrrole Values .Calculcted tor tifizoosNs 1 Values Found for the I Residue 538.67 (by difference); I

Oxygen. Nitrogenanon-a Gui-GO Assumed structure for CnH OaNs:

.o; t i

a n H;

The previous exampleillustraics a particularly advantageous feature of this invention, that is, if olefins are present. a is u ua ly-the ca e. in t e nit enc ntam hated petroleum tracti n it may b unn essa y o add ydroperoxides- The hydropcro des may be term d in si u y contacting w th air o oxy n- It has e n. found that t e hyd o a n pe oxid re cts muc more eadilyv w h t 'py l in the p esen e o catalytic qua tities of metal ion Amonzsthe me a i ns. b copp r, o n ese nd ce um a ery efie tive. Other ions of suitable redox potential with chang: ing valence may also be utilized. Such ions, when in their higher valence forms, react with hydroperoxides to form peroxide radicals. The increased reaction rate may be attributed to the generation of these peroxide radicals and the subsequent reaction of the pyrroles, The followingexperiments show the effect of metal ions on the reaction between .hydroperoxides and pyrroles.

EXAMPLE 1o Two moles per liter of pyrrole and t-butyl hydroperox? ide were added o b n e To par o the amp (1001 mole per liter of copper oleate was added. The peroxide number, determined according to the ferrous sulfate method e gn ct a t, Indus l and En nee ng Chemistry, Anal. Ed., Vol. 19, p. 976 (1947 was rev corded after 1 hour and 3 days. I

- The following table shows the data obtained:

Peroxide Number Copper after- Oleate,

mlL v. 1 h u 3 days ,410 r ty Hvdrop m d 3 3, 367 3,130 i I v 0 2, 700 3. 780 Pyrrole and t-Butyl Hydioperoxide (1001 299 0 For purposes of comparison, 2 moles per liter of tbutyl hydroperoxide were added to a benzene solution in the absence of any pyrrole. The above data clearly show that theamount of unreacted peroxide is considerably less when the copper oleate' has been added to the solution. This, of course, indicates that the action proceeded with greater rapidity.

shows the appearance EXAMPLE 11 Pyrrole'and various derivatives thereof were reacted with t-buty l hydroperoxide in benzene. The general procedure used was to add about 0.1 gram of pyrrole or its derivative to two samples of benzene, each of 5 ml. To one of the samples about 0.05 gram of cupric chloride was added. To both samples 0.4 ml. of t-butyl hydroperoxide was added. The samples were allowed to stand for one hour at room temperature. The following table of the samples.

TABLE IV Reactant with 't-butyl Reaction in the Reaction in the Hydroperoxido Absence of CuOl Presence of 011012 Pyrrole, ,No visible change Immediate exothermic after l'llour. reaction occurs and a dark brown precipitate is formed. 2,li-Dimethy l-pyrrole.- Solution turns yellow Solution turns dark in an hour. amber rapidly and a. brown precipitate is formed in about 6 mm. 2,4Dimethyl-3-ethy1- Yellow coloration in Solution turns dark "pyrrole. an hour. brown rapidly and precipitate is formed in 10 min. -Pheny1-pyrrole No visible change Medium red coloration I efterlhour. (Juli solution an our. Indole Haze vformation but- A-mber coloration of ittlo coloration in an solution inanhour. our. 2, 1u yl: ud9. So ution t rns da k solution turns a I brown-in 5 minutes amberrapidlyand a st y eci e i formed.

This table illustrates that'the reaction proceeds more rapidly in the presence of cupric chloride. When each of the solutions containing the cupric chloride was diluted with equal amounts of n-heptane, further amounts of precipitate were observed at the end of one hour.

Another method of removing pyrrole-type nitrogen compounds has been discovered in accordance with this invention. It has been found that pyrroles also react with sulfides and sulfoxides to form black polymeric substances. Though pyrrole-type nitrogen compounds are removed, e.g. indoles, carbazoles, the pyridines are not responsive to such treatment. However, .pyridines are not a cause of fuel instability. This is shown in the fact that when 40 ppm. of pyridine in a xylene solution was heated for 16 hours at 210 F. no sediment was formed and no coloration occurred. The desirability of removing pyrrolic nitrogen compounds has been discussed above. A wide variety of organic sulfides and sulf oxides can be utilized in accordance with this invention. Dialkyl, alkylaryl, diaryl sulfides and sulfoxides are examples of materials which may be utilized. The substituted derivatives of such compounds may be also used.

.By way of illustration specific compounds include dimethyl sulfoxide, indanyl p-toluyl sulfoxide, diphenyl sulfide. The hydroxy substituted sulfides and sulfoxides such as 2-phenyl-2-hydroxy-ethyl phenyl sulfoxide, 2-(1- hydroxy)-indanyl p-toluyl sulfoxide and bis-hydroxyethyl sulfide, are particularly suitable for use in this invention.

The following table indicates some of the sulfides and sulfoxides which were used for nitrogen removal in the examples of this invention.

TABLE V 8 EXAMPLE 12 0.003 mole/liter of sulfur compounds I, II, IV, V and VI was added to xylene containing 0.003 mole/liter of pyrrole. The solutions were stored at 210 F. for 16 hours and then the amount of sediment formed and the percent nitrogen in the sediment were determined. The following table indicates the data obtained.

The above data clearly indicate that an appreciable amount of the nitrogen is removed by the addition of the sulfur compounds.

EXAMPLE 13 The sulfur compounds listed in Table V were dissolved in xylene to give solutions of 0.003 mole/liter concentrations. To samples of such solutions 0.003 mole/liter of freshly distilled pyrrole was added. Then 200 ml. solutions containing the sulfur compounds together with Melting Point I 2-Indanyl p-toluyl sulfide II.... Z-Indanyi p-toluyl sulioxide III.... 2-Indanylp-to1uyl sultone IV 2-(1-hydroxy)-indanyl p-tolnyl sultoxidam V; (2-Phenyl-2-hydroxy)-ethyl phony] sulfoxide. 6

VI (2-Hydroxy)-0etadecyl phenyl sulioxlde..-.

SOCH:

Qso-om-oH-omm:

The preparation of such materials is shown in co-pending application Serial No. 777,861.

To further illustrate the advantages of this aspect of the invention, the followingexamples are given. The sulfur compounds added are referred to by Roman numerals which correspond to the compounds of Table V.

in the distillatesare shown in Table VII. v

pyrrole were stored in open 500 m1. Erlenmeyer flasks at 110 F. one month. After this period the samples were filtered and the filtrates were distilled from a steam bath at 15 mm. The colors of the samples after the storage, the amount of sediments and the nitrogen concentration TABLE VII Color of Sample Color of 3 Compound Pyrrole Sediment N in Distillate (led Added mgJlOO ml. Distillate after (ppm Appearance Tag- (p.p.m.) Two N) Robinson Months None None Colorless 25 Nil Colorless. None... 40 Yellow ti t 24 Nil 7.8 Brownish. I -10 Green 9 3. 2 2. 9 Light. 40 Dark 0.5 2.6 2.7 Light. 40 Yellow 24 Nil 40 Dark Green... 2. 4. 3 1. 4 Light. 40 Brown 5 1 3. 8 Light. 40 Brown 10 0. 6

From Table VII it is apparent that sulfides and sulfoxides convert pyrrole to sediment and residue. As a consequence, the distillation of such samples produces a stable hydrocarbon (xylene) with low nitrogen content.

EXAMPLE 14 Reaction of 2-indanyl p-toluyl sulfoxide and pyrrole in nitrogen atmosphere 0.003 mole/liter of both Z-indanyl p-toluyl sulfoxide and pyrrole and the same compounds alone were dissolved and colorless.

EXAMPLE 15 Removal of nitrogen compounds from kerosene (a) Bis-methyl sulfoxide and air.A crude oil mixture of 80% Officina and Gunipa (Venezuelan) was distilled in an atmospheric still with 15 theoretical plates. A cut obtained between 300 to 600 F. by ASTM distillation was treated in the following manner.

9.2 grams dimethyl sulfoxide and 1 liter of oil were placed into a 1200 m1. three-necked round bottomed fiask equipped with a thermometer, water condenser and sintered glass air inductor. Air was introduced into the mixture for 6 hours while it was kept between 87 to 92 C. and stirred by a magnetic stirrer. At the end of this period the mixture was left to stand overnight when 0.3 gram of dark brown oil had separated on the bottom of the vessel. This oil had a nitrogen content of 1% while the original nitrogen content of the oil was 20.2 ppm.

distilled to remove a 300 to 520 F. fraction. In (a) and (b) this fraction contained a nitrogen content of only 7 ppm. and 5.9 p.p.m., respectively.

What is claimed is:

1. A process for the denitrogenation of hydrocarbons containing pyrrole-type nitrogen compounds which comprises contacting 0.1 to 5 moles, per mole of said pyrroletype nitrogen compounds, of an organic compound selected from the class consisting of peroxides, sulfides and sulfoxides with said hydrocarbons, converting said nitrogen compounds by reaction with said compounds whereby a high boiling fraction of high nitrogen concentration is formed, and separating said fraction from said hydrocarbons, said hydrocarbons being of substantially reduced nitrogen content.

2. The process of claim 1 wherein the said organic compound is a sulfide.

3. The process of claim 1 wherein said organic oompound is a sulfoxide.

4. The process of claim 1 wherein the said organic compound is a peroxide.

5. The process of claim 4 wherein the fraction of high nitrogen concentration is formed in the presence of metal 10118.

6. The process of claim 5 wherein the metal ions are of the class consisting of cobalt, copper, iron, manganese, and cerium.

' 7. A process for the denitrogenation of hydrocarbons containing pyrrole-type nitrogen and olefins which comprises oxidizing said olefins to form peroxides in situ, reacting said peroxides with said nitrogen compounds and subsequently separating said fraction from said hydrocarbons, said hydrocarbons being of substantially reduced nitrogen content.

8. The process of claim 7 wherein said olefins are oxidized by the introduction of air into said olefins.

References Cited in the file of this patent UNITED STATES PATENTS 2,782,143 Bicek Feb. 19, 1957 2,832,723 Jezl Apr. 29, 1958 2,846,358 Bieber et al Aug. 5, 1958 

1. A PROCESS FOR THE DENITROGENATION OF HYDROCARBONS CONTAINING PYRROLE-TYPE NITROGEN COMPOUNDS WHICH COMPRISES CONTACTING 0.1 TO 5 MOLES, PER MOLE OF SAID PYRROLE TYPE NIRTOGEN COMPOUNDS, OF AN ORGANIC COMPOUND SELECTED FORM THE CLASS CONSISTING OF PEROXIDES, SULFIDES AND SULFOXIDES WITH SAID HYDROCARBON, CONVERTING SAID 